Umeå sits at 63°N, well inside the Arctic Circle zone of extreme seasonal variation. In June and July the sun barely sets — the famous midnight sun gives the city a dreamlike quality, with daylight stretching past midnight and the birch trees luminous in the long evenings. This is the best time to visit if you want warmth and outdoor activity, though the mosquitoes in the surrounding forests are fierce from late June onwards.
Winter is long, cold, and dark, with temperatures regularly dropping below -15°C and the river freezing solid. Locals ski and skate outdoors; the surrounding forests are good for cross-country skiing. This is the season for the Northern Lights, which appear here reliably from October through March on clear nights. The university keeps the city active and social through the dark months.
Autumn is underrated — September brings golden birch leaves and pleasant temperatures before the cold arrives. The Umeå Jazz Festival runs in late October, one of the better jazz events in the north. Spring, when the ice breaks on the river and the birches leaf out almost overnight, is brief and beautiful.